A variety of vitamin D derivatives are known to have useful physiological activities. For example, JP 6-23185B/1994 discloses that a 1α-hydroxyvitamin D3 derivative represented by the following general formula:
wherein R1 denotes an amino group or the formula OR′ where R′ denotes a lower alkyl group having 1 to 7 carbon atoms which is unsubstituted or substituted by a hydroxyl group, a halogen atom, a cyano group or an acylamino group, and R2 denotes a hydrogen atom or a hydroxyl group, is useful as a therapeutic agent for diseases caused by calcium dysbolism or as an anti-tumor agent.
1α,25-dihydroxy-2β-(3-hydroxypropoxy)vitamin D3 (also called as ED-71) which is one of the compounds covered by the above general formula is an active form of a vitamin D derivative having a bone forming action and thus is in a way to be developed as a therapeutic agent for osteoporosis.
Once such a vitamin D derivative is established as a therapeutic agent, it should be highly purified and be supplied in bulk and steadily. Therefore, it is desired to establish a method for manufacturing a vitamin D derivative as soon as possible.
In particular, ED-71 has been obtained only in an amorphous form and there is no reported isolation of ED-71 in a crystalline form.